T4 Endonuclease IV

Point mutants in the D2a region of bacteriophage T4 fail to induce T4 endonuclease IV.

We have studied the properties of presumptive point mutants in the D2a region of bacteriophage T4. Dominance tests showed that the D2a mutation was recessive to the wild-type allele. The mutations were shown to map in the D2a region by complementation against rII deletions. The D2a mutations were also located between gene 52 and rIIB by two- and three-factor crosses. The mutants are located at ...

T4 endonuclease involved in repair of DNA.

An enzyme activity, named T4 endonuclease V, was purified from T4-infected Escherichia coli. The enzyme induces single-stranded breaks in ultraviolet-irradiated DNA but does not act on native or heat-denatured DNA. The enzyme activity is dependent on the dose of ultraviolet irradiation, and the number of the breaks formed is approximately equal to the number of pyrimidine dimers present in the ...

Biochemical analysis of the substrate specificity and sequence preference of endonuclease IV from bacteriophage T4, a dC-specific endonuclease implicated in restriction of dC-substituted T4 DNA synthesis

Endonuclease IV encoded by denB of bacteriophage T4 is implicated in restriction of deoxycytidine (dC)-containing DNA in the host Escherichia coli. The enzyme was synthesized with the use of a wheat germ cell-free protein synthesis system, given a lethal effect of its expression in E.coli cells, and was purified to homogeneity. The purified enzyme showed high activity with single-stranded (ss) ...

Endonuclease II - a GIY-YIG enzyme of bacteriophage T4

Partial suppression of bacteriophage T4 ligase mutations by T4 endonuclease II deficiency: role of host ligase.

Endonuclease II-deficient, ligase-deficient double mutants of phage T4 induce considerably more deoxyribonucleic acid (DNA) synthesis after infection of Escherichia coli B than does the ligase-deficient single mutant. Furthermore, the double mutant can replicate 10 to 15% as well as wild-type T4, whereas the single mutant fails to replicate. When the E. coli host is also deficient in ligase, th...